| 1. |
- Fischer, Andreas, et al.
(författare)
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Chemistry and indoor air quality in a multi-storey wooden passive (low energy) building : Formation of peroxyacetyl nitrate
- 2014
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Ingår i: Indoor + Built Environment. - : SAGE Publications Ltd. - 1420-326X .- 1423-0070. ; 23:3, s. 485-496
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Tidskriftsartikel (refereegranskat)abstract
- Indoor air measurements were conducted in one unoccupied apartment of a 'near-zero-energy' residential building with a unique, wooden construction. Ozone, NO2, fine particles and volatile organic compounds, formaldehyde, acetaldehyde and peroxyacetyl nitrate (PAN) were measured under 'as is' conditions and after intentional intervention by adding ozone to simulate an ambient air ozone episode. Undisturbed concentrations were: O 3 5-10 ppb, NO2 5-8 ppb, fine particles 2000-5000 cm -3, formaldehyde 35 ± 5 μg/m3, PAN 0.3 ppb. During intervention, O3 was 50-60 ppb, NO2 15-20 ppb, fine particles 20,000-25,000 cm-3, formaldehyde 44 ± 2 μg/m3 and PAN 0.7-1 ppb. It was shown that chemical reactions had taken place in the indoor air. Ozone-initiated chemistry produced various aldehydes, PAN and, as a direct response to increased ozone concentrations, also fine particles. Calculations made by a simple model of PAN formation showed that an air change rate of around 0.2 h-1 would provide optimum conditions for PAN formation in a setting comparable to that of the investigated apartment. This air change rate is well below the Swedish national minimum of 0.5 h-1. Further, the calculations show that the non-photochemical PAN formation could be a consequence of mixing ozone and nitrogen dioxide with terpenes and acetaldehyde.
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| 2. |
- Fischer, Andreas, et al.
(författare)
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Ozone removal by occupants in a classroom
- 2013
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 81, s. 11-17
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Tidskriftsartikel (refereegranskat)abstract
- Ozone concentrations were measured in a classroom with and without occupants, with the purpose to quantify effects on indoor O3 concentrations. The teacher and 24 11-year old pupils each removed O3 at a rate, first order in O3, corresponding to a rate constant of (2.5±0.6)×10-5s-1 in the present locality and to a deposition velocity of 0.45cms-1. The O3-removal caused by the occupants was approximately 2.6 times larger than that of the available surfaces belonging to the classroom and its furniture. Observation of 6-methyl-5-hepten-2-one and 4-oxopentanal at maximum concentrations of 0.2ppb and 0.7ppb, respectively, suggested squalene from human skin oil as a reactive, ozone-consuming substance. There are indications of a source of 4-oxopentanal in the classroom, even some time after the pupils left for the day. The work presented is important for a proper description of indoor exposure, both to ozone itself and some of its reaction products when trying to quantify relations between exposure and health effects.
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| 3. |
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| 4. |
- Shannigrahi, Ardhendu Sekhar, 1965, et al.
(författare)
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n-Alkanoic monocarboxylic acid concentrations in urban and rural aerosols : Seasonal dependence and major sources
- 2014
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Ingår i: Atmospheric research. - : Elsevier BV. - 0169-8095 .- 1873-2895. ; 143, s. 228-237
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Tidskriftsartikel (refereegranskat)abstract
- We report new data on the abundance and distribution of n-monocarboxylic acids (n-MCAs) in fine- and coarse-mode aerosols in rural and urban areas of Sweden, and determine their possible sources. Overall, C6–C16n-MCAs accounted for ~ 0.5–1.2% of the total PM10 (particulate matter ≤ 10 μm) mass. In general, the C12–C16 fraction was the most abundant (> 75%), with the exception of wintertime samples from a rural site, where C6–C11 acids accounted for 65% of the total C6–C16n-MCA mass. Positive matrix factorization analysis revealed four major sources of n-MCAs: traffic emissions, wood combustion, microbial activity, and a fourth factor that was dominated by semi-volatile n-MCAs.Traffic emissions were important in the urban environment in both seasons and at the rural site during winters, and were a major source of C9–C11 acids. Wood combustion was a significant source at urban sites during the winter and also to some extent at the rural site in both seasons. This is consistent with the use of wood for domestic heating but may also be related to meat cooking. Thus, during the winter, traffic, wood combustion and microbial activity were all important sources in the urban environment, while traffic was the dominant source at the rural site. During the summer, there was considerable day-to-day variation in n-MCA concentrations but microbial activity was the dominant source. The semi-volatile low molecular weight C6–C8 acids accounted for a small (~ 5–10%) fraction of the total mass of n-MCAs. This factor is unlikely to be linked to a single source and its influence instead reflects the partitioning of these compounds between the gas and particle phases. This would explain their greater contribution during the winter.
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| 5. |
- Shi, Bingbing, 1983, et al.
(författare)
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Intermediate air filters for general ventilation applications: An experimental evaluation of various filtration efficiency expressions
- 2013
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Ingår i: Aerosol Science and Technology. - : Informa UK Limited. - 0278-6826 .- 1521-7388. ; 47:5, s. 488-498
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Tidskriftsartikel (refereegranskat)abstract
- Neither the European standard nor the US standard for classification of intermediate class filters comprises testing of filter performance with respect to ultrafine particles (UFPs) or particles of the most penetrating size (MPPS). This could turn out to be a major lack in classification standards since UFPs have been pointed out as a serious health hazard. In this study, fractional efficiencies of eight new full-scale bag filters and twenty-three new filter medium samples were determined. The influence of air velocity and aerosol type was investigated, and correlations between efficiencies for UFPs (EFUFPs), MPPS-sized particles (EFMPPS) and 0.4 μm-sized particles (EF0.4μm) were established. The tested bag filters were challenged by four aerosol types: a neutralized atomized oil aerosol, the same oil aerosol but non-neutralized, a non-neutralized thermally generated oil smoke, and a “natural” indoor aerosol. The tests were carried out at different air velocities through the filter medium, ranging between 0.08 m/s and 0.22 m/s. The relationships that were observed between EFUFPs, EFMPPS, and EF0.4μm appeared to be linear within the observed filtration efficiency ranges. These relationships were similar regardless of the test aerosol type used, but somewhat different for glass fiber filters than for charged synthetic filters. Generally, EFMPPS was 10–20% lower than EF0.4μm. The influence of air velocity variations on the size resolved efficiency was determined. The glass fiber filters showed practically the same fractional efficiencies regardless of whether the test aerosol was neutralized or not. However, the charged synthetic filters showed substantially lower efficiencies when tested with the non-neutralized aerosol compared to the case when the aerosol was neutralized.
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| 6. |
- Shi, Bingbing, 1983, et al.
(författare)
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Removal of ultrafine particles and particles of the most penetrating size by new intermediate class filters
- 2011
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Ingår i: Proceedings of the Indoor Air 2011 Conference, Austin, TX, USA, 6 pages.
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Konferensbidrag (refereegranskat)abstract
- Twenty-three new filter samples, including three different medium types, were tested in a small scale test-rig using a Scanning Mobility Particle Sizer (SMPS). The filtration efficiencies for ultrafine particles (UFPs) and particles of the most penetrating particle size (MPPS) were determined. The filters were of class F5-F9 according to the European filter standard, which roughly corresponds to MERV9-MERV15 according to the US-standard. The filters were challenged by the indoor aerosol prevailing in the laboratory. Additional tests were made using an oil aerosol. With the indoor aerosol, charged synthetic filters showed substantially higher MPPS efficiencies than glass fiber and uncharged synthetic filters of the same class did. With the oil aerosol, the different filter media types, belonging to the same filter class, showed similar efficiencies. The oil aerosol drastically reduced, or eliminated, the electrostatic filtration mechanism. For example F7 and F8 filters not influenced by electrostatic mechanisms typically showed 40% and 50% removal of MPPS particles respectively.
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